Efforts to reduce dependence on fossil fuels for transportation fuel and as feedstock for industrial chemicals have been undertaken for decades, with a particular focus on enabling economic feasibility of renewable feedstocks. Heightened efforts are being made to more effectively utilize renewable resources and develop “green” technologies, due to continued long-term increases in the price of fuel, increased environmental concerns, continued issues of geopolitical stability, and renewed concerns for the ultimate depletion of fossil fuels.
Cellulose in biomass is commonly used as a feedstock for biofuel production. For example, cellulose can be used to produce ethanol. Cellulose can also be used to produce furan-based biofuels by way of 5-(halomethyl)furfural, such as 5-(chloromethyl)furfural (CMF). CMF can be converted into 5-(ethoxymethyl)furfural, a compound considered as a promising diesel fuel additive. Alternatively, CMF can also be converted into 5-methylfurfural, another compound considered as a promising a biofuel candidate.
The production of CMF from cellulose was first described in the early 1900s. Currently, various synthetic routes are known in the art to produce CMF. Crude CMF is typically an oily residue that can be distilled to obtain a purified liquid CMF. Solid CMF can then be obtained from the purified liquid CMF at 0° C. See e.g., Szmant & Chundury, J. Chem. Tech. Biotechnol. 1981, 31, 205-212; Liu et al., J. Phys. Chem. A, 2011, 115, 13628-13641; and U.S. Pat. No. 7,829,732. Other methods have also been described to isolate CMF and other 5-(halomethyl)furfurals such as 5-(bromomethyl)furfural (BMF). For example, CMF and BMF may be isolated by recrystallization via slow evaporation of a solvent. See e.g., Fenton and Gostling, J. Chem. Soc., Trans., 1901, 79, 807-816; Fenton and Gostling, J. Chem. Soc., Trans., 1899, 75, 423-433; and Hibbert and Hill, J. Am. Chem. Soc. 1922, 44, 176-182. The use of distillation, however, to isolate 5-(halomethyl)furfural can be energy-intensive on a commercial scale.
Thus, what is needed in the art are improved methods to produce 5-(halomethyl)furfural, without the need for distilling 5-(halomethyl)furfural, the reaction solvent, and/or the recrystallization solvent to isolate 5-(halomethyl)furfural. What is also needed in the art is a commercially-viable method to produce 5-(halomethyl)furfural in solid form, which can more easily be handled, transported and stored than 5-(halomethyl)furfural in liquid form.